An evaluation of the Level 1 blood warmer series

Abstract

SummaryThe Level I blood warmer series comprises three infusion sets and two blood warmers qf diferent power outputs. All systems were,found to be extremely eficient, with the larger 500 series capable qf warming the equivalent of80 units of blood un hour almost to bod?, temperature. Key wordsEquipment; blood warmer.Hypothermia can be a serious problem after massive blood transfusion and the need for maintenance of normothermia under these circumstances is firmly established. The major problem associated with conventional blood warmers are the limitations in flow because of the resistance of the tubing in the apparatus and the very poor thermal conductivity of the plastic of the infusion sets. As a result these warmers become very inefficient at flows greater than about 150 ml/minute.The Level I series* is a new type of blood warmer that has recently become available in this country, and we report an investigation of it using a previously described method.' ApparatusThe Level I series consists of two components, a hardware system and a disposable giving set. HardwareThe warming unit is attached to an infusion stand and heats water to 40°C. This is then circulated through an aluminium single counter current heat exchanger (Fig. 1) which is an integral part of the infusion sets and is attached to the infusion stand. The latter also incorporates an adjustable height pole. Two independent circuits continuously control and monitor the water temperature and will

Prevention of Hypothermia during Surgery

“…Different measures are available for the prevention and treatment of perioperative hypothermia. Convective warming and fluid warmer are among those devices which have been proven as effective tools in maintaining intraoperative normothermia 1–4 . However, direct comparisons of these devices are lacking as well as studies which investigate the effect of combined convective warming and fluid warming.…”

Peri‐operative warming devices: performance and clinical application

“…High flow rates At faster flow rates above 9 l.h À1 , the Level 1 â infusor (Level 1 Technologies Inc, Rockland, MA, USA) was found to achieve higher distal temperatures in laboratory studies when evaluated against heating blocks, air convective fluid warming, heating elements, steel foil heat exchangers and water bath warmers [14,18,[22][23][24][25]. The Level 1 system incorporates a countercurrent water heat exchanger via a large-bore thermally conductive aluminium tube interface, which is designed to maximise heat transfer without compromising flow [24].…”

“…The Level 1 system incorporates a countercurrent water heat exchanger via a large-bore thermally conductive aluminium tube interface, which is designed to maximise heat transfer without compromising flow [24]. However, the recommended delivery fluid temperature of 37°C was still only rarely achieved at these flow rates [18].…”

Active warming of saline or blood is ineffective when standard infusion tubing is used: an experimental study

“…1 A fluid warmer represents an efficient tool for warming infusates. 10,11,[19][20][21][22]23 There are some discrepancies among the performances of fluid warmers, those using countercurrent technology warming blood and saline more effectively than do fluid warmers that use either dry heat or water bath technology. 2 3 At flow rates usual in children, one can consider these differences as minimal and the fluid will be effectively warmed at the output of the warming device.…”